GOST 23116.2-78

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  ГОСТ 23116.2-78

INTERSTATE STANDARD

Date of introduction 01.07.79

This standard sets the spectrographic method for the determination of mercury (in mass concentration of mercury from 510^-5 % to 510^-3 %) in cadmium of high purity.

The basis of spectrographic determination of mercury in cadmium on the method of «three standards» with the evaporation of mercury from the crater of the carbon electrode in the arc DC.

(Changed edition, Rev. No. 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis and security requirements — according to GOST 23116.0.

(Changed edition, Rev. No. 1).

2. APPARATUS, REAGENTS AND SOLUTIONS

The quartz spectrograph medium dispersion type of ISP-30 spectrograph or diffraction-type DFS-8, or STE-1 being the illumination system of the slit.

Spectromancer of PS-18.

Generator DC arc.

Microphotometer designed to measure pucherani spectral lines (complete set).

Libra torsion bar type W with a weighing error of no more than 0.001 g.

Analytical scale with a weighing error of no more than 0,0002 g.

Electrodes, carbon, OS. h 6 mm in diameter, with a crater size of 4x15 mm and contradictory a length of 30−50 mm, one end sharpened to a truncated cone with ground diameter of 1.5 mm.

Mercury GOST 4658.

Lithium chloride.

Cadmium GOST 22860.

Potassium chloride according to GOST 4234.

Crucibles of graphite or a graphite-chamotte with lids.

Files for sharpening electrodes according to GOST 1465.

The laboratory furnace, crucible, allowing the temperature to 500 °C.

Spectrographic plates of type I or P.

Samples comparison. The basis for the preparation of the samples is metallic cadmium with mercury content less than 110^-5 %. The basic sample containing 0.5% of mercury, prepared as follows. The calculated linkage of mercury wrapped in cadmium plate, so that the mercury was inside. In a graphite crucible, heated to a temperature of approximately 400 °C under a flux consisting of potassium chloride and lithium chloride in a 1:1 ratio, melt a portion of the cadmium in the melt are immersed a sample of mercury wrapped in cadmium plate. Thoroughly mixed melt is then poured into the mold. The primary dilution of the sample with cadmium 100 times receive the first comparison sample. Then by serial dilution of each newly obtained sample basis 2−3 times prepared a series of working samples. The prepared samples carefully analyzed by a colorimetric method according to GOST 19 674 units.

Sec. 2. (Changed edition, Rev. No. 1, 2).

3. ANALYSIS

Mercury determination is carried out on the quartz spectrograph medium dispersion being a condenser. The slot width 0,020 mm. the Weight of the portion of sample or reference sample (300 mg) in the form of sawdust is placed in a hole in the bottom carbon electrode to a depth of 15 mm, a diameter of 4 mm and thoroughly compacted with a kick ball made of organic glass. Between the electrodes the arc is ignited, the DC power of 8 A. the exposure Time 2 min, the distance between the electrodes of 2.5−3.0 mm.

Spectra of samples and calibration samples are photographed three times on the same photographic plate.

Sec. 3. (Changed edition, Rev. No. 2).

4. PROCESSING OF THE RESULTS

4.1. In the spectrogram, using microphotometry measure the blackening of analytical lines of mercury Hg I 253,652 nm and the surrounding background (right of the line). According to the measured values of S_l+f and S_f, using the characteristic curve, determine the logarithms of the intensity of the lines and background lg (I_l+ I_f) and the logarithm of the background intensity lg I_f. Then I_l= (I_l+ I_f) — I_f. Calibration graphs constructed in the coordinates lg I, lg Withwhere With the mercury concentration in the calibration samples. For the calibration chart find the mercury content of cadmium.

To construct the characteristic curve of photographic plates simultaneously with the samples and the samples of the comparison spectrum photographed through a nine-iron platinum reliever.

The final result of the analysis taking the arithmetic mean of two parallel definitions (each definition of the three spectrograms).

The difference between the two results of parallel measurements with a confidence probability P = 0.95 does not exceed the value of permissible differences (d_n) calculated by the formula

d_n = 0,3 ,

where is the arithmetic mean of the two comparable results of parallel measurements.

The difference between two results of analysis of the same samples with confidence probability P = 0.95 does not exceed the value of permissible divergence (d_a), calculated according to the formula

d_a = 0,3 ,

where is the arithmetic mean of the two comparable test results.

(Changed edition, Rev. No. 2).

4.2. (Deleted, Rev. No. 1).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 16.05.78 No. 1298

3. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

4. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

5. EDITION with Amendments No. 1, 2 approved in December 1983, December 1988 (IUS 4−84, 3−89)